Cook pasta until not quite done (a few minutes less than package directions call for). Drain and set aside.

In a large pot, melt butter over medium-high heat. Add garlic and saute for a few minutes, then add mushrooms and salt and saute a few minutes more. Pour the wine in and cook several minutes, until the liquid reduces by half.

Sprinkle the flour in and stir to incorporate. Cook a few minutes more, then slowly add the chicken broth, being careful to stir well. Cook a few minutes more until the mixture thickens.

Reduce heat to medium-low and add cream cheese in small blocks, stirring well. Don’t be alarmed if the cream cheese doesn’t completely melt at this point, it will eventually. Add the chicken and the peas and stir to combine. Season with salt and pepper.

Add the cooked spaghetti and stir to combine. Pour into a greased (or sprayed) large baking dish. Mix breadcrumbs with 2 tablespoons melted butter and spread over casserole. Bake at 350 degrees for 20-30 minutes, until casserole bubbles.